CB-846608/2011

ClearFire EconomizerModel ECF

Integral or External

Addendum to manuals 750-295 CFH and 750-269 CFV

ECF Economizers

1-GENERALThe Model ECF economizer is a stainless steel coil tubearrangement using extended heating surface fins tomaximize heat transfer. Flue gas from the boiler passes overthe coiled tube, which conveys incoming feed water. Feedwater preheated in this way eliminates the need for a steamfeed water heater, with resulting efficiencies of up to 87% innon-condensing applications.

The ECF is offered as either an integral or an external unit.The integral ECF-I is designed for Model CFH high pressuresteam boilers and can be installed in a new or existing boilerwithout the requirement for additional space above orbehind the boiler. The economizer is installed in the smokebox at the rear of the boiler with water connections at therear.

The external ECF-E is designed for Model CFV boilers andmay also be used for CFH low pressure steam boilers. Theeconomizer mounts in a vertical position and connects tothe boiler flue gas outlet.

For all ECF applications, feed water is pumped continuouslythrough the economizer. A two position 3-way divertingvalve - controlled by the boiler’s normal on-off level control- sends heated feed water either directly to the boiler formake-up, or re-circulates heated water back to the feedsystem as a method of preheat.

The ECF economizers are virtually maintenance free, havingno moving parts.

2-INSTALLATIONConsult submittal data for specific weights and dimensionsto ensure a well designed and safe installation.

The external economizer is shipped ready to be mounted inthe vertical position as originally specified (consult thefactory if a change in the gas flow direction is desired).

For existing retrofit installations, ensure that the boiler hasbeen turned off and has cooled. Follow established lockout/tagout procedures.

For retrofit installations the economizer is installed in linewith the existing exhaust stack or duct unless otherwisenoted. Generally a section of the exhaust stack is cut and removed to accommodate the insertion ofthe economizer. The remaining portion of the exhaust stack above the cut should not exceed 200 lbsand must be adequately supported.

When calculating total length of breeching the external economizer should be considered as 2 elbowsor 10 feet total equivalent length of ductwork.

Apply expansion joints (supplied by others) as required by the installation to ensure that no outsideforces from thermal expansion to either the exhaust gas connections or to the piping will be permitted.

Economizer fin tubes

Flue gas flow, internal economizer

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ECF Economizers

Ensure that the economizer is level before final bolting into position.

Liquid connections are connected with NPT threaded fittings. Liquid piping should include shut-offand bypass valve piping in the event the economizer is required to be isolated.

NOTE: The safety relief valve provided with the economizer must be located between any isolationvalves and the economizer and within close proximity of the economizer. Liquid piping to and fromthe economizer should allow the economizer to be filled at all times especially when flow could stop.

Softened water is highly recommended with any C-B economizer. Refer to the boiler manual foradditional water treatment recommendations. Proper water treatment is essential to the longevity,safety, and efficiency of your boiler system.

Generally, schedule 80 or schedule 40 steel pipe is used in the piping installation. In some applicationsother piping material may be needed. Consider the type of liquid, operating pressures andtemperatures, and any corrosive elements in the liquid or in the atmosphere when determining thebest piping material for your installation. The use of unions and/or flanges is recommended whereisolation might be required. Stainless steel piping is recommended if using non-deaerated water.

If a circulating pump is part of the system being installed, a ball or flow control valve installed on thesuction side of the pump and one on the discharge side of the pump will allow for easier pump removaland replacement.

Piping should include valves of dependable manufacture, properly rated for operating conditions, inorder to reduce the possibility of an undetected leak.

A safety relief valve is provided as required. It should be located at the economizer and pipedseparately and safely to the drain. Do not connect safety valve piping to the boiler blowdown piping.

A manual vent valve is provided and should be installed at the highest point in the piping system. Thevent valve purges air from the system, especially during filling and initial start up.

While condensing should be avoided when operating the CFH or CFV boilers, small amounts ofcondensation can be expected due to cold startups and other transient conditions. For this reason acondensate drain is provided at the bottom of the smoke box (CFH) or stack outlet (CFV). Forinstallations with external economizers a second drain is provided at the economizer. See the pipingdiagrams for details.

Condensate drain piping can be piped to the floor drain. Condensate piping should include a watertrap to prevent the escape of flue gas. For external economizers the boiler and economizer drains canbe trapped and drained separately, or they may be piped to a common drain with a single p-trap. Seepiping diagrams.

To ensure proper drainage, the external economizer must be installed in the upright position.

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ECF Economizers

External economizer installation

2.1- Feedwater Valve

Wire the feedwater 3-way valveas shown. In this diagram,control panel terminals 36 and37 are connected to the pump/valve relay on the LWCO/Levelcontrol. Terminals 23 and 24are connected to 24VAC power(installations may vary; consultthe wiring diagram providedwith the boi le r for wi r ingterminal assignments).

2.2- Special Installation Considerations

Freeze protection concerns: During a system shutdown where combustion halts for an extended periodof time (other than normal cycling), cold air will travel back down the stack and exhaust breechings,through the economizer and into the combustion source. If the cold air is below freezing, it could freezethe finned tubing and cause a rupture, ultimately destroying the economizer. For potential freezingapplications where the water flow might stop, a manual system shut down routine should beincorporated.

Insulate piping and exhaust ducting as required.

Consult the circulating flow diagram (if applicable) for your application with regard to the piping layoutand components. Exhaust and liquid inlet and outlet thermometers are included for the installation.Capped tees, one on the liquid inlet side and one on the liquid outlet side, should be incorporated intothe piping installation to allow a descaling solution to be used with the economizer in place. The

VALVE

24VAC

LWCO/LEVEL CONTROL

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ECF Economizers

manual vent valve can also be used for this purpose. Consult the factory for suitable descalingsolutions.

The economizer relief valve should not have a set pressure rating higher than the rated pressure of theeconomizer. To avoid relief valve leakage, ensure that valve set pressure is sufficiently higher than deadhead pressure of the feed pump.

It is recommended that the pipe and surge/feed tank (if included) be insulated to reduce heat loss.

A feed pump suitable for continuous service is required. A single-stage or multi-stage centrifugal pumpis recommended (single-stage for low pressure boiler applications and multi-stage for high pressure).

For applications with the potential of producing condensation in the economizer and flue, corrosionresistant materials should be used in flue design.

3-STARTUPFilling the Economizer - first ensure the boiler has been filled to the normal operating water level.

Verify the 3-way valve has been properly wired to the water level control.

The feed pump should be in manual operating mode.

Make sure all valves are in the proper position for startup (see diagram; refer also to piping diagramsin Section 6).

• CLOSED: manual fill valve [1] economizer bypass valve [2] drain valve(s) [3]

• OPEN: manual bleed/vent valve [4] economizer isolation valves [5]

FROM ECONOMIZER

TO BOILER

TO ECONOMIZER

TO FEED TANK

FEEDWATER

PRESSURE RELIEF

67

4 8

CLOSEDOPEN

* OPEN to fill economizer CLOSE before starting boiler

*

1 - MANUAL FILL VALVE2 - ECONOMIZER BYPASS VALVE3 - ECONOMIZER DRAIN4 - MANUAL BLEED / VENT VALVE5 - ECON. ISOLATION VALVES6 - 3-WAY FEED WATER VALVE7 - ADJUSTABLE ORIFICE VALVE 8 - PRESSURE RELIEF VALVE

Valve positions for initial startup

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ECF Economizers

Begin with the orifice valveopen approximately half wayand the 3-way valve in therecirculation position.

Start the feed pump. Checkthe pressure gauge andadjust the orifice valve tomaintain feedwater pressurewith in 10-20 psi o f theboiler’s operating setpoint.

When water can be seenescaping through the ventvalve, close the valve.

Verify proper operation of the3-way valve by opening thewater column drain. Whenthe wa te r l e ve l d r opssufficiently, the valve shoulda l low f low to the bo i le rfeedwater inlet. Close drainbefore continuing.

Pu t t he f e ed pump i nautomatic mode and start the boiler.

When the boiler reaches operating pressure, adjust the orifice valve as necessary. System pressureshould be consistent regardless of the position of the 3-way valve. This is to ensure steady flow throughthe economizer and to avoid steaming downstream of the economizer outlet.

Observe operation of the system for several feedwater cycles.

NOTE: C-B requires that liquid must be flowing through the economizer at all times while theeconomizer is in use. This is to avoid steaming in the coil. Upon cold startup of a full boiler, provisionsmust be made to ensure water flow through the economizer. Assure sufficient flow to prevent anyunwarranted temperature and pressure buildup within the liquid side of the economizer.

If the final exhaust temperatures are too low (causing undesirable condensing in the flue) or if thedesired feedwater temperature is not met, adjust the orifice valve to attain the desired objective.

The economizer may be bypassed if it is first drained. After operating in bypass mode, before theeconomizer is returned to service it must be allowed to cool and must be filled with water.

Important!If liquid is introduced into a hot economizer, severe damage can result and will void any warranty. Contact C-B for applications where the economizer is requested to run dry at temperatures above 500 deg F.

NOTE: SYSTEM FLOWDOES NOT FOLLOWARROW ON VALVE BODY

3-Way Valve

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ECF Economizers

4-MONITORING PERFORMANCEIt is recommended to inspect the core or coil if the performance (liquid temperatures leaving and Btu/hr. recovery) begins to decrease. A good practice of maintenance is to keep a performance schedulestarting when the economizer is installed to compare with any future changes.

While the economizer is in a clean, like-new condition, note and record the following:• Water flow rate• Boiler firing rate• Liquid inlet and outlet temperatures• Exhaust gas inlet and outlet temperatures• Steam pressure gauge reading (if applicable)

This information will provide a point of reference in the event of a future fouling condition.

A simple method of determining whether the economizer is performing properly is to monitor the exittemperatures on the liquid and gas sides while in the new condition to establish a base of comparabledata. If the stack temperature leaving the economizer is higher than normal and the liquid exittemperature is lower than normal, then the external heat transfer surface is fouled or scaled on theinside of the tubing. This requires cleaning as soon as possible during a convenient shut down period.

If the economizer pressure relief valve discharges, it is likely that there is no or little liquid circulatingthrough the economizer. Check the pump operation and repair or replace as necessary. DO NOTATTEMPT TO REMOVE OR REPLACE THE PUMP UNLESS THE PUMP, PIPES AND LIQUID HAVEBEEN ALLOWED TO COOL. You may also need to check for flow restrictions in the piping and/or theeconomizer.

If the economizer inlet and outlet temperatures are approaching being equal, this may be a pumpproblem and/or a scale accumulation in the finned tubing. Remedy as indicated above. It is alsopossible that the fin coils are severely fouled. Refer to section 5 below for cleaning.

5-MAINTENANCEAs stated in the general description, the economizers are mechanically maintenance free.

A routine physical inspection of the heat transfer core area will be dependent on the temperatureconditions and combustion quality within the flue gas stream. NOTE: Ensure that the boiler is off andis cool, and that the economizer is cool before attempting to inspect or clean the fin coil(s).

On natural gas or propane fired applications, with clean exhaust conditions, physical inspection willbe minimal if proper combustion at the burner is maintained.

In the unlikely event of an accumulation of dirt on the fins (i.e. a 1/16" thickness build up on the fins),the fouled finned tube area can be manually cleaned by blowing air with a lance assembly across thefins. If high pressure air is not available, an industrial vacuum cleaner may be substituted.

If a waterside inspection shows a buildup of scale due to inadequate water treatment, descaling shouldbe performed before resuming operation. Investigate deficiencies in the water treatment program andcorrect accordingly.

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6- PIPING EXAMPLES

CFH boiler - integral economizer with feed tank

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ECF Economizers

Integral economizer, no feed tank

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ECF Economizers

CFH low pressure steam applications

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ECF Economizers

CFV, external economizer with feed tank

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ECF Economizers

CFV, external economizer no feed tank

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ECF Economizers

7-PARTS

MANUAL

ECONOMIZER

(Integral Model ECF-I shown)

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ECF Economizers

8-DIMENSIONS AND CONNECTION SIZES ECF external economizer

DRY WEIGHT (LB) 50 80 105 135OPERATING WEIGHT (LB) 53 84 112 143

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